August 7th, 2012

GOING GREEN

A new tool will improve the way UDOT monitors and optimizes traffic signal performance.

UDOT is using a new online tool for automated traffic signal performance measures.

To keep traffic moving, traffic engineers aim to create signal timing plans that allow most cars to reach an intersection on a green light, according to UDOT Traffic Signal Operations Engineer Mark Taylor.

When cars reach the intersection on green, concerns such as waiting and frustration, traffic delay, pollution from idling and wear and tear on vehicles and pavement are all reduced. And the dilemma zone, the point at which drivers decide to stop or proceed through the signal, is also reduced, which improves the safety at intersections.

But establishing and maintaining efficient signal plans typically costs thousands of dollars to develop. Engineers use resources, including equipment or people to monitor signal operations, collect traffic volume counts and then model and create a signal plan, explains Taylor. Since collection and modeling methods are time and resource intensive, updating the signal plan is usually only done every few years.

Plus, typical modeling and collection methods only providing a limited, snap-shot view that degrades over time as traffic patterns change. To really improve signal operation, “we need to know in real time where the problems are so we can make corrections to operations to improve traffic flow,” says Taylor.

UDOT is using a new online tool, called Signal Performance Metrics, originally developed by Indiana Department of Transportation and Purdue University. The system uses Dilemma Zone radar detection already in place along with reconfigured software provided at no charge to UDOT by developers at Wavetronics and Econolite.

The system locates and counts cars, places a time stamp on every car and then pulls that data into online graphs that can be observed in real time. “We’ve got over 500 sites where we already have Dilemma Zone detectors installed at intersections,” says Taylor.

Signal Performance Metrics has a potential benefit for signal operation everywhere but especially on weekends when signals operate with plans designed for week day off-peak hours. Taylor says the system “will help us be much more proactive with traffic signal timing seven days, twenty four hours a day.”

UDOT Director John Njord has charged traffic engineers with creating a world-class traffic signal system and employing Signal Performance Metrics is a step in that direction. Taylor is pleased about the ability to see in real time whether existing signal plans are good or bad so signal timing can be changed as needed, without using limited funding to monitor corridors or intersections. He thinks the traveling public will eventually see better traffic progression and less delay. “This is big for us.”